310 DR A. J. WHITING ON THE 



comparatively few in a similar mass of the splenic pulp, seems to me to be insufficient 

 ground for concluding that blood formation is more active in the former than in the 

 latter, for the cells of the pulp in all probability reach the blood stream much more 

 easily and rapidly than do those of the marrow ; the spleen has a very large and free 

 blood supply, while the bone-marrow has a comparatively poor blood supply ; the splenic 

 pulp is surrounded by a contractile and elastic framework, but the red marrow is inclosed 

 in a rigid case of bone ; the spleen undergoes rhythmic contraction every minute and 

 periodic enlargement during digestion, when the spaces of the pulp may be thoroughly 

 flushed out, but, as far as we know, no such change affects the bone-marrow. 



Summary of Effects of Hemorrhage. 



The following are the principal changes that were observed in our experiments as a 

 consequence of the abstraction of blood : — 

 A. On the Blood : — 



(1) A fall in the number of red corpuscles. 



(2) A fall in the specific gravity. 



(3) A fall in the percentage of haemoglobin. 



(4) An immediate and transient increase in the number of leucocytes. 



(5) A late diminution in the average size of the red corpuscles. 



(6) A transient appearance of giant cells. 



(7) A transient appearance of nucleated red cells. 



(8) An increase in the number of blood plates. 

 B On the Spleen : — 



(1) A slight increase in size. 



(2) The appearance of numerous giant cells. 



(3) The appearance of proportionately numerous erythroblasts and nucleated 



red cells. 

 The latter two facts afford, we think, strong positive evidence in favour of the view 

 that the presence of giant cells is a frequent, if not an invariable, accompaniment of 

 blood formation ; and, together with the phenomena exhibited by the giant cells of the 

 blood on the warm stage, strongly suggest the probability that the giant cells produce 

 erythroblasts in the spleen. 



On Artificial Anemia in the Rabbit. 



But I have some negative evidence to offer, derived from the examination of the 

 spleen of an anaemic rabbit. 



Both Neumann and Freyer * and Bizzozero and Salvioli t found that, in rabbits, 



* Neumann (29), p. 446. f Bizzozero (30), p. 599. 



